This application claims the priority of German application 5 298 06 552.2, filed in Germany on Apr. 9, 1998, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a weft thread insertion device for an air jet loom comprising at least one main nozzle block mounted on a sley and movable together with the latter, said main nozzle block having at least one individual nozzle, devices for supplying compressed air to the main nozzle block with which one or more stationary distributor blocks are associated, said distributor blocks each having at least one outlet, from which outlet compressed air is supplied through a flexible pressure line to the inlet of a respective individual nozzle of the main nozzle block.
In known weft thread insertion devices for air jet looms, the main nozzle block mounted on the sley is supplied with compressed air by flexible pressure lines. The air is supplied to the individual nozzles through distributing arrangements permanently mounted on the machine frame and connected by the abovementioned pressure lines with the individual nozzles. Since the main nozzle block is mounted on the sley and consequently performs oscillating pivoting movements together with the sley, the pressure lines between the distributor block and the main nozzle block must be of a certain length so that problem-free air supply to the main nozzle block is guaranteed in every position of the sley. For example, kinking of the flexible pressure lines can temporarily change their cross section with each movement of the sley, and a certain amount of waste air is associated with each change in cross section. In addition, it was previously difficult, because of the relatively long pressure lines and the limited space available, to run the pressure lines without intersection and simultaneously to keep them as short as possible. However, with a certain length of each pressure line there is the problem that the pressure buildup upstream of the main nozzle block is delayed or a pressure loss occurs that must be corrected by increasing the diameter of the pressure lines or by control measures.
A system with improved air supply to the main nozzle block is described in European Patent Document EP 619 391 B1. In this case, the pressure lines between the distributor block and the main nozzle block are kept short, while the distributor block is located approximately centrally between the end positions of the movement of the sley, with the main nozzle block performing the pivoting movements together with the sley. As a result, the mechanical stress on the lines and the pressure loss can both be reduced.
In a main nozzle block with a pre-nozzle block, however, it is still difficult to run the plurality of individual pressure lines for the shortest distance without intersections and without kinks between the distributor block and the nozzle blocks in question.
Hence, a goal of the invention is to improve the weft thread insertion device for air jet looms of the species recited at the outset.
This goal is achieved by providing an arrangement wherein the one or more stationary distributor blocks at least partially surround the main nozzle block independently of the position of the sley.
The invention is based on the fact that the distributor block or blocks are so arranged that they at least partially surround the main nozzle block regardless of the position of the sley.
Because the inlets for the individual nozzles of the main nozzle block are advantageously distributed over the circumference of the main nozzle block and the outlets of the distributor block may be located according to the invention directly opposite the associated inlet, the advantage is obtained that the length of the pressure lines between the outlet and the inlet can be reduced to a minimum. It is also possible to run the pressure lines without intersection in a simple fashion so that the individual lines do not rub against one another during weaving. Another advantage is that as a result of the arrangement of the distributor blocks according to the invention, all of the pressure lines have essentially the same length so that the delays in building up pressure upstream from the main nozzle block are the same.
In a first embodiment, a plurality of individual distributor blocks is provided, arranged approximately in the shape of an L or U around the main nozzle block. The individual distributor blocks can be arranged in a plane perpendicularly to the lengthwise axis of the sley or they can be staggered with respect to one another in space in the direction of the lengthwise axis of the sley. The staggered arrangement, for example when a so-called tandem arrangement of pre-nozzles and main nozzles is used, has the advantage that both nozzles can be supplied with compressed air through relatively short pressure lines.
According to another embodiment, the distributor block is made in the shape of an arc or the letter U, with the outlets being arranged at constant or variable intervals on the arc or the U of the distributor block.
In known fashion, a controllable valve is associated with each outlet on the distributor block, so that the air supplied to each individual nozzle can be regulated.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.